1. Field of the Invention
This invention relates to a process for hydrogenating carboxylic acid esters to primary alcohols in solution under mild conditions utilizing alkali doped Group VIII metal catalysts supported on carbon.
2. Brief Description of the Background of the Invention Including Prior Art
Carboxylic acid esters, as a class, are not readily susceptible to hydrogenation to produce primary alcohols under mild conditions. Generally, severe conditions are required, such as temperatures well above 150.degree. C. together with reaction pressures in the order of 13.8 MPa to 20.7 MPa (2000-3000 psig). In addition, the hydrogenation process generally requires a catalyst which is frequently not selective, such as Raney nickel, copper-chromite, or zinc-chromium oxide. See Organic Reactions, Vol. 8, pages 1-27 (John Wiley, 1954).
Catalytic hydrogenation of carboxylic acid esters represents an important industrial source of primary alcohols, which are useful in a wide variety of known applications such as in producing gums, resins, perfumes, wetting agents and the like. For example, 1-decanol is commercially produced by catalytic hydrogenation of coconut oil fatty acids and their esters under high pressure. Sulfonated derivatives of 1-decanol are useful as surface active agents. Also, 2,2,2-trifluoroethanol, CF.sub.3 CH.sub.2 OH, useful as an intermediate in producing the anesthetic, CF.sub.3 CHClOCHF.sub.2, is produced by the heterogeneous catalytic hydrogenation of 2,2,2-trifluoroethyl trifluoroacetate, CF.sub.3 COOCH.sub.2 CF.sub.3, as described in U.S. Pat. No. 4,072,726 (Nychka et al. to Allied Chemical Corporation, 1978).
A. Ozaki et al. in U.S. Pat. No. 3,770,658 issued Nov. 6, 1973 disclose a catalyst comprising at least one element selected from the group consisting of transition metals belonging to VI-B group, VII-B group and VIII group of the Periodic Table and at least one element selected from the group consisting of alkali metals belonging to the I-A group of the Periodic Table, both elements being substantially in the metallic state.
This catalyst has not been employed in the hydrogenation of esters.
An example of soluble hydrogenation catalysts is disclosed in our copending, commonly assigned U.S. patent application Ser. No. 070,583 filed Aug. 29, 1979 which discloses a method for preparing anionic group VIII metal hydride complexes by reacting a neutral group VIII metal complex, or adduct thereof, with a group IA metal cation radical anion complex also called "metal arene" such as potassium naphthalene, in a solvent therefor, such as tetrahydrofuran or diethyl ether. New and improved catalysts for catalytic hydrogenation of carboxylic esters to primary alcohols are constantly being searched for.